[Amps] 4CX1500B's -- worth using?

[donroden at hiwaay.net]

Quoting Ian White GM3SEK <gm3sek at ifwtech.co.uk>:
> The *physical* power dissipation of the 1000A grid cannot be literally
> zero. Eventually Eimac changed the data sheet to allow up to 5mA of grid
> current  to flow "for peak signal monitoring purposes"... but for some
> reason the maximum rated power dissipation has always remained at
> literally "zero"
> 73 from Ian GM3SEK

The ALC in the Collins 30S1 is derived from a transformer between the  
bias supply and the tube. To get ALC, Grid current must flow .....  
even if slightly.
ZERO grid current = Zero ALC.

Possibly a better ALC circuit is one that samples the rf as it comes  
into the amp and the user sets the ALC for zero grid current on a per  
band basis.  Then the 4CX1000 could then operate in a "true" zero grid  
current mode.

Don W4DNR